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tv   [untitled]    May 8, 2012 5:00pm-5:30pm PDT

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i'm lawrence corn field with the department of building inspection. we are here with a bump of experts to talk about earthquake issues in san francisco. we are at one of san francisco's most wonderful spots. this is at the cliff house. it's a wonderful place. if you don't come down here, you should come and take a look. you can see the earthquake fault that is actually caused the 1906 earthquake. today we're doing a little tour about earthquake issues and we have dr. lou gill ton, pat
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buscovich and frank rowland , geotech -- gee owe technical engineer. are we safe standing here? >> (inaudible). >> okay. right behind us, we can see all the way down san francisco's ocean beach and water front all the way down to points stig identity. what is that. >> pacifica is sticking out. beside that the muscle rock, the next promenade to the north and san andreas fault. >> muscle rock is what? the middle ground? >> in the fog. >> the bunch is just coming out. >> it's the point furthest south. >> okay. and why is that important to us? >> muscle rock is where the san andreas fault comes into san
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francisco cocaine and city a nd -- county and city. >> this is -- >> coming out into the water. >> going into the water, and out past fill rock and frank, where are we going from there. >>çó port race, it comes up between valleja so,. >> that's balinsa and point rat fault comes in between those two. >> okay. how far offshore is the fault where where we stand? >> about a mile and a half to two miles offshore. >> i have a question. i always hear that earthquake shaking and earthquake hazards are increased the closer you are to the fault. do you think that's right? >> that's correct. >> okay. so we're pretty close here, so that means that should the fault
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rupture on the san andreas fault, we have more potential damage than if you're further away based on if the soils were uniform. >> the (inaudible) decreases the further distance from you. the ep i center is further offshore and occurred in '06. the first initial shock, the small one felt in san francisco, and 20 or 30 seconds later, the big earthquake took off in both directions going north and south. >> okay. >> what you're talking about is something that engineering communities really acknowledged if you're in five kilometers of that fault, and particularly if the slip goes from one point to another point, you're going to have more ground shaking, similar to if you're standing next to a railroad track and the
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training is coming to you and you have something called a doppler effect and getting louder and louder, the earthquake simplistically does the same thing. if the san andreas slips down there and comes this way, within this five kilometer zone of san francisco, the richmond/sunset is going to shake dra mat cli harder. >> in 1906 it didn't matter because the rupture went from the ep pi center off of lake merced and went in both directions. so the doppler effect was felt in both direction. >> also in 1906, nobody was here, right? >> well sue sudro was here. >> if a tree falls in the forest, and nobody hears it, well now there's a lot of housing here and somebody's
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going to feel it. >> i saw a map that this area was severely shean in 1906 although almost no houses were here. we can expect the same action? >> i think you have to different differentiate, but you may not get as much damage here as you would at the shore line or san francisco bay. this is a rough site -- >> if you're going to be out in richmond, it's right there. >> yeah. i have heard that along ocean beach here and a few blocks in, there are some special hazards because of the fact that there's water underlying the ground and so on. is that -- >> yeah. there are hazards associated with anu$quake. obviously the firstçó one is ground shaking which we talked about. then there are other gee owe
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logic hazards and that's where the sand turns to quick sand, especially the sands that are beneath the water level. other hazards associated is lateral spedding. after the soil lick -- becomed and flows, the dense --ification. >> if i eat a box of cereal and it's full, it's two inches down. >> that's true. damages associated with those phenomenas are severe. you've seen pictures along valencia street where the hotel is lying on its side. >> we're going down there. >> out in the sup set there were no homes, so we don't know how much dense densification will or
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and it will depend ton level. >> we have a lot of theories. >> yes. >> we don't think we're wrong, we just hope we never have that earthquake. the problem is -- >> well, we're going to have it. >> the reality is reear going to have it. >> so i have a question for lou. a lot of people, all around the world, have different theories for what causes earthquakes. here, you know, we sort of like to imagine that we have some scientific basis, so i brought along something from japan, actually. i wonder if you can talk about the basis of the fact that in japan it's pretty well acknowledged that it's the rigling of the catfish underground that causes earthquake. >> in china's is the bulls. >> it tees bulls. >> i'm afraid i'm not a buy ol
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gist. >> in san francisco it's the dog over there barking that causes a problem. >> when i was in college a thousand years ago at uc berkeley, this was before plate techtronix, there was a theory the earth sat on a frog and every once in awhile the frog would burden of proof and that -- burp and that was the earthquake. >> i'm sure it's the catfish. >> okay. we're going to go on down to a couple other sites and take a look at some of the impacts that earthquakes might have in san francisco. >> here we are in richmond and i want to point out though the earthquake centennial isñr a big
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deal this month and we have earthquake centennial wine bolted by the apen wine company commemorating the earthquake. >> i don't think it's 100 year old wine. >> no it says vintage 2003, should be just right to drink in april. we're here in richmond rein have the experts and the new experts, harvey, the scrap house dog. >> geologist and we have -- >> (inaudible). >> but we're here because for a number of reasons. we can look at the typical san francisco home and the kiengdz of vulnerables that it might have. we also want to talk about something i always heard talked about is micro zonation, where your house is on the ground affects how it's going to perform in the earthquake.
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>> one of the highest predominating pack or. if you're on rock, that's goodçó news. it depends on the period. it dependsñr on how the building is built. out here in the richmond it's similar to sunset. we're on what's called do you -- dune sand area. in the old days before homes were built here, the san franciscans would use this part of the city to dump their garbage. so they would drive to richmond or the sunset, dump their garbage and spread the dune sand over the garbage and innocently come along and build a home on dune sand not knowing five or ten feet below the surface there would be garbage not knowing this was one of those location. >> it is exactly the location. this house hasçó been settling since it was built the last ten
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years. it settled in the middle around three irjs. you can see settlement by looking at the -- if you were able to get inside you would see the foundation cracking. if you went into the finished mortion of the house you can see cracks in the wall you can put your hand in because it wasñr built on an oold garbage dump. >> we're talking about this on i theoretical issue. sit okay to build? is the richmond a good place. we have to say are you on top of an old farm pond or creek or garbage dump? it can have profound impacts in the settlement over long term and if there's an earthquake, that can amplify the ground shaking; is that right? >> absolutely. it can affect the behavior of the home. one of the things pat brought up is the wide garbage door opening
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i guess it's an issue you guys call soft story? >> exactly. >> what is that? >> it means the upper floors are rigid and in an earthquake the building will wanted to drift sideways a certain amount. if the upper floor the rigid and it doesn't occur there, it occurs on the first floor and if it leans so far the build willing lose stability and collapse. that's one of the projects the city is working on to try to come up with an economical efficient way to retrofit the doors so they don't become projects unto themselves. >> i think there's a limited likelihood in the middle of the block, buildings are going to collapse. you have buildings on either side holding it up but it's going to pound -- >> the term pounding was used a lot and it was in reference to the marina district ton homes in the corner were pound upon by
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the ad jay sent street. >> out into the street. >> either they fell into the street or they -- they basically collapsed into the street. >> these soft story building where you might have option for garbage doors or commercial window displays. >> at the corner. >> or you might have other uses on the corner where you have soft, basically big openings are a problem at the corner and you have vulnerability in both direction. now you have harvey the wonder dog, butñi you might want to shw what we're working on. >> install these clips on thega. >> into the door,ñi not the fra. >> and i've installed this already at my house to try it out. we've done preliminary testing and it gives us fantastic loading and cost meñi $5ñi to
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purchase and install theñrñi cl. >> as theúwzll push this is way itñiçó france fers the force -- transfers the force. these doors are strong, 3 ork 4,000 pounds. >> and the load goes down to right here. >> and you're basically jamming the garage door into the frame. i1ñ even the door with windowsçó and louvers, is stronr than the frame around it and what actually was failing was the building, not the garage door. >> make shoo you are you explain you don't attach it to the door because you won't be able to open the door. >> so we'll be trying to present some information on how we do it and make recommendations when we finish the testing in the next omonth or two. the city is looking for ways to cost effectively retrofit building. this are other things you should do that are cost effective. >> the important point to make is we're all striving to make
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our homes more earthquake resistant, not earthquake proof. we cannotñi earthquake proof lie we can waterñi proof jackets and rain coates are water proof, but our home and property can be made to be resistant and the more recent codes are -- allow us to be more earthquake resistant than the older codes. >> that'sç"right. nothing is earthquake proof. some people build buildings thaó are designed toñr be continuousy operational, even after anñi earthquake,çó very expensive. >> just hospitals and schools and places that have to be operate. >> all we can do is reduce the impact of earthquakes. >> those are new buildings. on existing homes there,'s the garage door basing your water heaters, adding anchor bolts,
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plywooding or strapping your posts. on a house like this with this clipping, what can do, what i've done for probably less than $5,000 get a reasonable comfort level, your house will be damaged but sleeping there at night. >> we can reduce the impact of earthquake so get back to so-called normal life as quickly as we can. one of the elements is having people be able to stay in their homes. >> instead of on the street. >> one of our serious goals. we'll move on to other interesting areas of the city. welcome to the mission. >> yes. >> this is frank's home. >> i grew up in the mission. in fact i grew up a couple blocks up the street, forest and 18th. >> we were talking ability issues of earthquake safety have to do with a number of things. the soil you're on, how strong or vulnerable your building is and of course, they have to do with what the earthquake is whether it's a little shakera
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big one on hayward or san andreas fault. >> remember at the beach we talked about the hazards associated with earthquake, the liquid faction, lateral spreading -- [sirens]. >> we're standing at 18th and valencia and if you notice the street slopes down and to the south the street slopes down, so we're at a low point. the low point was the old channel of rye owe dolores or river of pain and emptied into mission creek which fed mission bay. >> it came up the street on 18th street and we're walking down. >> from 18th and market right on down and emptied into what was a trib tear of butary of mik
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and because of that, loose sands were deposited and these loose sands were under the water in 1906 who the violent earthquaking occurred, the santdz lick -- sands liquefiedd flowed laterally. half a block up from this spot was the valencia hotel the famous picture where you see the second story became the ground floor. >> we'll walk up there in a second. frank, what happened to the creek? did it get filled with sand when people built the mission? >> it's still there. actually, the city and county of san francisco filled many the creek and put in large sewers and the large sewers underground that actually collect the water and of course, valencia point -- >> so it's channelized
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underground and dumps out towards mission. >> not all of it. the issue is still the same. the loose sand is still present so in the next major earthquake, we can expect to see the same types of movement that occurred in 1906. >> people say what kind of effect are we having from the earthquake and it's going to be the same types of things that happened in past earthquakes and same location. >> you can go to shot well street which in '0 '6 there are great shots of the victorian tilted over. in '89 when i was working for you they had torn down the victor i can't answer andñi buit edwardians, so same thing. so two out of two -- >> same area, same thing. >> most of the new developments that are occurring many the mission district, including
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affordable housing projects, they are conscious of their poor soil conditions and have improved the ground so the ground will perform better and the structures will be much more earthquake resis teant. >> there's a disparity -- basically anything built after the '70s and on, and construction before that really didn't have a whole lot of seismic resistance. >> in retention to what you're sitting on. >> so you say if we were to have a repeat of the 1906 earthquake, hope we never do, we're going to have settlement, we're going to have lateral spreading, we're going to have -- >> guisers coming out of the ground with jetties. >> i hope we don't have that. >> we'll see many of the same phenomena that occurred in 1906. we don't know how well the sunset or richmond is going to
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behave, but we have theories that allow us to compute the kind of settlement that's going to occur, the kind of movement. >> here on valencia street we are on the enl of the stream next to a lake which is where mission dolores was -- >> we're actually in the lake. >> in the lake. somewhere in this lake or built on top of the lake is a number of buildings. where a number of build that's were seriously damaged or destroyed in 1906 including the famous valencia hotel, is that the name of it? which was located approximately a half block to the nomplt when the earthquake occurred, the lower floor, which pat refers to as a soft story, collapsed and so that the second floor became the ground floor. and then the building leaned over. many buildings, in fact, most if not all of the buildings in this area, including the church at 16th aep and color res --
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>> the cathedral -- >> the old bazilica but the mission remained because it was a strawn --ñr staunch building, but the bazilica was demolished. >> there was -- the ground motions were amplified by the wet soils? >> yeah. and you saw similar conditions in 1989 in portions of the marie yarks watson vil. >> shot well a block or two away which experienced the same damage in '06 based on historic pictures, you saw the rebuilt building in the exact same shape. >> that's great and we're going to one more spot. here we are in one of san
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francisco's most historic neighborhoods on jackson street between montgomery and sampson. i understand from pat buscovich when san francisco was built, there were no addresses; is that right? >> no. actually your address was jackson between mont dwommery and sampson. that's all you got since there were so few people here. >> everybody knew who everybody was. this might have been on the wharf. we're right at the edge of the bay. if we take a look you can see on the alley here, this curvy line, which is one of the indicators of the edge of the bay, many of the streets down in this part of town were originally wharfs. >> the ships would come in forña few years until the '4 9 gold rush they would offload and theseñr were wharfñi house buildings. gold hit and the ships never left.
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>> so we're talking about earthquake issues and how the soils affect the earthquake stability of your home and building. here we'reñi on an area which ws filled there is in the engineer filled. nobody figured out we need to exact it. it was filled with old ships and this sort of stuff. there's endless reminders -- in fact, i want to point out this is an old self--styled snrash block and carried -- splash block and carried water off the edge of the sidewalk. this is the edge of the sidewalk right here. >> there wasn't much sidewalk. this is before we had concrete so it might have been kobl stone. it was only wide enough to pass. >> everything got filled and looks modern, how does that affect build. >> this side is the original shore line.
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that side the fill amplifies the ground motion and the 1850's to now, engineers and builders have tried to mitigate the issues of the soil conditions. >> okay. i guess the message we're trying to say where you're on soils that have been filled or we know there's problems, takeçó extra precaution totion try to minimize the damage. >> absolutely. a lot of buildings, very early buildings, like a building down the block built on redwood los angeles, most houses built in san francisco, unless they're modern,ñi post '75, did nothino mitigate for the soil conditions. if you're the owner of the house, there are other things you can and should consider with the advice of a çó geo technical engineer. >> these are all brick buildings
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in here. they all pretty much survived the 1906 earthquake and fire. >> in fact, there's a plaque here saying they had to bring a hose a mile over telegraph hill to put out a fire. >> because all the liquor was d here. that's important. >> actually, this bidding behind us, if we can turn around, survived the earthquake and fire. the shutters are still there and part of the historic fabric on the second floor. i've worked on this building for 20 years. one of things they did after the fire -- after the earthquake just before the fire is they lined their roof with brick debris as a fire stop. >> that closed the metal shutters. >> closed the metal shutters and the building survived the fire and that brick rubble is on the roof is w. a roof over it. i has to do some work on it and
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left it in place because it's a fair break. >> is that a structural problem having a brick roof? >> these building were built pretty stout for graft load but no no it's not a problem but we considered it. >> one of the problems we see the city faces with different building times and wood frame brick and contreat buildings, what is the final message that as a structural engineer we should be passing along to the people of san francisco. >> i think people should not think it's a hopeless cause. they need to hire an engineer and buy an hour of that engineer's time to discuss options, costs, benefits and make decisions other than, well, i survived the '89 earthquake, so my building is okay. that is not something they should -- >> that was a very moderate earthquake, unfortunately much
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stronger ground motion and earthquake. my experience, and probably yours, a little bit of hazard mitigation goes a long way. a couple sheets of fly wood, garage door bracket, the curving of benefit is pretty steep for that first 2, 3, 4, $5,000 encourage people to put in the basic they think they need to keep their building inhabitable after an earthquake. >> in the marina, one had anchor bolts, one dofnlt the one without anchor bolts has substantial damage. the curve is huge -- (inaudible). >> in you need help call the department of building inspection we're happy to help you and give you whatever advice and refer you to the structural
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engineer's association. our number for general information, 558-6205 and we'll transfer you to somebody who can provide you the information and help you retrofit your house. thank you very much and see you soon. >>. touring england was a time when robert as mentors were being challenged by a quickly growing middle-class. for endeavour's crew of new artists began to assert themselves, offering new definitions of the athletics of arts and beauty. over 180